Tetrabiblos

TET-ruh-BIB-lohs

Definition

The *Tetrabiblos* is a four-book astrological treatise written in Greek by Claudius Ptolemy in Alexandria in the mid-2nd century CE; some manuscripts title it *Apotelesmatika* ("effect-producing things"). Book I lays the philosophical and physical groundwork of the art. Book II turns to mundane and weather prediction — the astrology of nations, climates, and seasons. Books III and IV cover the birth chart itself, including length of life, character, fortune, and the manner of death.

In Tradition

Among the technical texts of Hellenistic astrology, the *Tetrabiblos* is one of two great surviving handbooks, the other being Vettius Valens' *Anthology*. Holden reads Ptolemy's book as, in important ways, a pared-down and selective take on the standard Greek astrology of his day — it leaves out much of the working material on lots, derived houses, and specific planet-in-sign readings that other Hellenistic writers kept.

In Practice

Traditional astrologers today use the *Tetrabiblos* as a primary source for Ptolemy's account of essential dignities (the terms in three versions, and triplicities sorted by sect — whether the birth is by day or by night), the aspects, his case for the tropical zodiac (I.22), the doctrine of length of life (III.10), the theory of the four humoral temperaments, and Book II's framework for mundane and weather prediction. Since Ptolemy steadily leaves out techniques his contemporaries relied on, you'll usually see the *Tetrabiblos* studied alongside Dorotheus and Valens, which together fill in the fuller Hellenistic picture.

Historical Origin

The *Tetrabiblos* was composed c. 150 CE. Holden notes that Ptolemy's astrological writings did not circulate widely until the end of the 3rd century, and that Vettius Valens — in Alexandria a generation later — shows no awareness of them. The Greek text passed down through Late Antique commentaries by Hephaestio of Thebes and Porphyry, reached medieval Europe through 12th-century Latin translations from Arabic intermediates (notably Plato of Tivoli's *Quadripartitum* of 1138, from Ibn Ridwan's commentary), and was first put into English by J. M. Ashmand in 1822 (still public domain). Modern editions include Robbins (Loeb 1940) and Hubner (Teubner 1998).

Further Reading

  • Claudius Ptolemy, Tetrabiblos (trans. J. M. Ashmand, 1822)
  • Claudius Ptolemy, Tetrabiblos (trans. F. E. Robbins, Loeb Classical Library)
  • James H. Holden, A History of Horoscopic Astrology